Fig. 1. Schematic diagram of MEET/DPMED design process Fig. 4. Knowledge base of DPMED Expert System Approach in Design of Mechanical Components submodules into equal reduction ratios, with each ratio being a square root of the total ratio. The user has the option of changing these defaults. One of the possibilities of designing the details of the trans- mission is to have one of the reduction units equal to the lowest reduction ratio, which is 1.23 in our case. MEET decides that the ratio of the second module should be 2.91. Oe eee ee: ON eee ee ee ee ee eee ee ee ee the pinion would be initialized to 18 and the number of teeth in the mating gear would be 22 (18 times the reduction ratio). The program would then use knowledge about critical goals to determine if the wear or the bending criteria is critical. In this exam- ple since the user has chosen Steel RCS55 for the pinion and Steel RCSS for the mating gear, the pro- gram uses its knowledge base to infer that the wear criterion is critical. The program first satisfies the wear-criterion, and then checks to see if the bend- ing criterion is satisfied. The face-width constraint is checked for both wear and bending criteria. The number of teeth for the pinion, the number of teeth for the mating gear, and the pitch of the gear are the independent parameters that are modified to deter- mine the next best move. Presently, we modify only one parameter at a time to determine the set of pos- sible moves. The best move is determined by how far the calculated face-width is from a recom- mended value determined by the constraint and picking the one that is the closest. Notice, it is not necessary that the same parameter be changed dur- ing each subsequent move nor is it necessary that the direction of change of the parameter (increase
